| 1. |
- Aamodt, K., et al.
(författare)
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Alignment of the ALICE Inner Tracking System with cosmic-ray tracks
- 2010
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 5
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Konferensbidrag (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 mu m in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10(5) charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.
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| 2. |
- Singhal, R., et al.
(författare)
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Reynolds Stress Gradient and Vorticity Fluxes in Axisymmetric Turbulent Jet and Plume
- 2021
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Ingår i: Lect. Notes Mech. Eng.. - Singapore : Springer Nature. ; , s. 403-411
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Konferensbidrag (refereegranskat)abstract
- The relation between the Reynolds stress gradient and the vorticity fluxes in a turbulent shear flow has been known since the time of G. I. Taylor. With recent advances in scientific computing, this question has received a renewed attention. In this work, we present results from a well-resolved direct numerical simulation of an axisymmetric turbulent jet and plume. The simulation reproduces the self-preserving features of the two flows reported in the literature and satisfies the identity relating the Reynolds stress derivative to the vorticity fluxes, to a reasonably good degree, establishing the veracity of the simulation. The axial derivative term in the identity is shown to be negligibly small, particularly when the jet/plume is in a self-preserving state. The radial profiles of the two vorticity fluxes for the jet and plume are nearly identical, suggesting a similarity of the underlying structure. The significant result is that the vorticity flux term involving the radial vorticity and azimuthal velocity is non-zero in the core of the jet as well as plume, while it is zero in the outer region of these flows. Furthermore, this term, in the core of the flow, is equal in magnitude (but opposite in sign) to the second flux term relating azimuthal vorticity and radial velocity. Coherent vorticity in the outer region of the jet/plume is in the form of hairpin vortices whereas in the core of these flows it shows a more complex shape.
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| 3. |
- Andersson, Martin, et al.
(författare)
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SOFC Modeling Considering Internal Reforming by a Global Kinetics Approach
- 2009
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Ingår i: Solid Oxide Fuel Cells, Eleventh International Symposium (SOFC XI). - 9781566777391 ; 25:2, s. 1201-1210
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Konferensbidrag (refereegranskat)abstract
- Fuel cells (FCs) are promising for future energy systems, since they are energy efficient and fuel can be produced locally. When hydrogen is used as fuel, there are no emissions of greenhouse gases. In this study a two dimensional CFD (COMSOL Multiphysics) is employed to study the effect from porous material surface area ratio on reforming reaction rates and gas species distributions for an anode-supported solid oxide fuel cell (SOFC). FCs can be considered as multifunctional energy devises, combining (electro-) chemical reactions, heat exchange, gas- and ionic transport. All these functions are strongly integrated, making modeling an important tool to understand the couplings between mass-, heat-, momentum transport and chemical reactions. Steam reforming takes place at the nickel material surfaces in the anode and water-gas shift reaction occurs where fuel gas is present. Benefit from the internal reforming is that the energy conversion efficiency will be higher, compared to the case of pure hydrogen as fuel.
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| 4. |
- Singhal, Pranshu, et al.
(författare)
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Key Environmental Performance Indicators (KEPIs): A new approach to environmental assessment
- 2004
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Ingår i: Electronics Goes Green 2004 (Plus): Driving Forces for Future Electronics, Proceedings. ; , s. 697-702
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Konferensbidrag (refereegranskat)abstract
- A new Key Environmental Performance Indicators (KEPIs) approach has been developed considering the perspective of a designer who may like to improve the environmental performance of the products but has limited resources and understanding of complex environmental issues. This approach empowers the designer with indicators like the area of PWB, the amount of precious metals etc which account for the physical and chemical characteristics of the product and its components. The indicators can be used for setting guidelines, benchmarking, monitoring and improving environmental performance. These indicators are easy to use, and require little time and data for assessing the environmental performance. The KEPIs approach greatly reduces the reliance on the product chain for gathering of data and allows the manufacturers to make big leaps, in improving the lifecycle environmental performance of the products, on their own.
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| 5. |
- Singhal, Rohit, et al.
(författare)
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Turbulent Diffusion of Scalar and Heat in an Off-Source Heated Steady Round Jet
- 2022
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Ingår i: 12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022. - : International Symposium on Turbulence and Shear Flow Phenomena, TSFP.
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Konferensbidrag (refereegranskat)abstract
- We study, using direct numerical simulation (DNS), the properties of a steady jet heated externally in a heat-injection zone, the rate of heat addition being proportional to the local concentration of a scalar. We examine the turbulent diffusivities of the scalar concentration, the temperature and the axial momentum, and compare their values with those for unheated jets and plumes. We also include results from the available literature and compare them with our results where possible. We find that external heat addition decreases the turbulent scalar diffusivity, leading to a decrease in the ratio of scalar to velocity flow widths relative to the unheated jet to a value that is largely insensitive to the precise details of heat addition, expect for one study. We also find that while the turbulent thermal diffusivity also decreases, the ratio of temperature to velocity flow widths is similar to those for unheated plumes. Our results suggest that further studies of off-source heated jets are warranted.
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